The perception of dyspnea in patients with mild asthma

Somatosensory amplification - An old construct from a new perspective

The paper reviews and summarizes the history and the development of somatosensory amplification, a construct that plays a substantial role in symptom reports. Although the association with negative affect has been supported by empirical findings, another key elements of the original concept (i.e. body hypervigilance and the tendency of focusing on mild body sensations) have never been appropriately addressed. Recent findings indicate that somatosensory amplification is connected with phenomena that do not necessarily include symptoms (e.g. modern health worries, or expectations of symptoms and medication side effects), and also with the perception of external threats. In conclusion, somatosensory amplification appears to refer to the intensification of perceived external and internal threats to the integrity of the body ("somatic threat amplification") rather than amplification of perceived or actual bodily events only. Practical implications of this new approach are also discussed.

Mechanisms, measurement and management of exertional dyspnoea in asthma: Number 5 in the Series "Exertional dyspnoea" Edited by Pierantonio Laveneziana and Piergiuseppe Agostoni

Asthma is a heterogeneous condition, with dyspnoea during exercise affecting individuals to a variable degree. This narrative review explores the mechanisms and measurement of exertional dyspnoea in asthma and summarises the available evidence for the efficacy of various interventions on exertional dyspnoea. Studies on the mechanisms of dyspnoea in asthma have largely utilised direct bronchoprovocation challenges, rather than exercise, which may invoke different physiological mechanisms. Thus, the description of dyspnoea during methacholine challenge can differ from what is experienced during daily activities, including exercise. Dyspnoea perception during exercise is influenced by many interacting variables, such as asthma severity and phenotype, bronchoconstriction, dynamic hyperinflation, respiratory drive and psychological factors. In addition to the intensity of dyspnoea, the qualitative description of dyspnoea may give important clues as to the underlying mechanism and may be an important endpoint for future interventional studies. There is currently little evidence demonstrating whether pharmacological or non-pharmacological interventions specifically improve exertional dyspnoea, which is an important area for future research.

Activity limitation and exertional dyspnea in adult asthmatic patients: What do we know?

Limitation of activity is the most cited symptom described by uncontrolled asthma patients. Assessment of activity limitation can be undertaken through several ways, more or less complex, subjective or objective. Yet little is known about the link between patients sensations and objective measurements. The present review reports the current knowledge regarding activity limitation and symptom perception (i.e., exertional dyspnea) in adult patients with asthma. This work is based on references indexed by PubMed, irrespective of the year of publication. Overall, patients with stable asthma do not have a more sedentary lifestyle than healthy subjects. However, during a cycle ergometric test, the maximal load is reduced when FEV1, FVC and muscle strengths are decreased. Additionally, during the six-minute walking test, mild asthma patients walk less than healthy subjects even if the minimal clinically important difference is not reached. The major complaint of asthma patients when exercising is dyspnea that is mainly related to the inspiratory effort and also to dynamic hyperinflation in some circumstances. Finally, the administration of bronchodilator does not improve the ventilatory pattern and the exercise capacity of asthma patients and little is known on its effect on exertional dyspnea. The present review allows to conclude that until now there is no gold standard test allowing the objective assessment of "activity limitation and exertional dyspnea" in asthma patients.

The Interpretation of Dyspnea in the Patient with Asthma

Physicians have noted dyspnea in severely ill asthmatic patients to be associated with fright or panic; in more stable patients dyspnea may reflect characteristics including lung function, personality and behavioral traits. This study evaluates the symptom of dyspnea in 32 asthmatic patients twice: first when acutely ill and again after an initial response to therapy. Spirometry was performed, dyspnea quantified (Borg scale), and panic assessed with a specialized measure of acute panic (the acute panic inventory (API)) in the 32 patients before and again after treatment. After treatment, questionnaires to evaluate somatization and panic disorder were also administered. When acutely ill, both the API and all spirometric measures (PEFR; FEV1; IC) correlated with dyspnea. Multiple linear regression showed that measures of the API, the peak expiratory flow rate, and female sex taken together accounted for 41% of dyspnea in acute asthma. After treatment, the API again predicted dyspnea while spirometric data did not. Those subjects who described themselves as having chronic panic disorder reported high grades of dyspnea after treatment also. We conclude that interpretations of the self-report of asthma differ between acutely ill and stable asthmatic patients.

Persistent airflow obstruction in young adult asthma patients

BACKGROUND

Lung function determined by spirometry and the severity of dyspnea correlate weakly in asthma patients. We attempted to determine the risk factors in asthma patients having persistent airway obstruction despite of having only mild subjective symptoms, and to examine the possibility of improving FEV1 by treating asthma on the basis of the bronchodilator change in FEV1.

METHODS

We examined asthma patients in their 20s and who visited Sagamihara National Hospital for the first time over a period of four years, by reviewing their clinical records. They underwent tests on the bronchodilator change in FEV1 and a test of airway hyperresponsiveness to histamine dihydrochloride.

RESULTS

One hundred thirty-eight subjects (mean age, 25.6 years; 51 males, 87 females; current smoking, 30.4%; history of childhood asthma, 48.6%) were enrolled. Among them, 18.8% (26/138) showed persistent airway obstruction (postbronchodilator FEV1/FVC (%) <80%). Using the multiple logistic regression model, we found that history of childhood asthma and smoking history were the significant isolated risk factors for persistent airway obstruction. Moreover, we determined that the factors associated with the reversibility of airway obstruction in asthma patients without subjective symptoms were history of childhood asthma.

CONCLUSIONS

In this study, patients not undergoing treatment for asthma were examined. History of childhood asthma and smoking history may be the risk factors for persistent airway obstruction in the asthma patients with mild subjective symptoms. Tests on the bronchodilator change in FEV1 should be performed in patients with history of childhood asthma and smoking history, even if they have only mild subjective symptoms.

Mild asthma in overweight women: A new phenotype?

BACKGROUND

Epidemics of asthma and overweight have been linked recently. They might be associated with systemic inflammation. In asthma hyperresponsiveness to adenosine (AMP) is more closely related to inflammation than to methacholine (MCh). The aim of the study was to determine responsiveness to AMP and MCh in overweight compared with normal weight asthmatics.

METHODS

Thirty women were enrolled (19 overweight) with mild controlled asthma according to GINA. A Body Mass Index (BMI) less than 25kg/m(2) was considered as normal and a BMI above 25kg/m(2) as overweight. We assessed the recent control of asthma (ACQ), pulmonary function tests, bronchial responsiveness to MCh and AMP (PC(20) and O'Connor two-point dose-response slope), perception of symptoms (Borg scale), and blood inflammatory markers (leptin and hs-CRP by ELISA).

RESULTS

Overweight had a significant lower dose-response slope of the MCh challenge (p=0.009) as compared to normal weight patients, whereas no significant difference was observed for AMP challenge (p=0.27). Overweight patients had higher intercepts of the Borg scale measured before the MCh and AMP challenge tests (p=0.01 and p=0.03). Plasma leptin (p=0.001) and hs-CRP (p=0.05) concentrations were higher in overweight than normal weight patients. There was no correlation between challenges and inflammatory markers.

CONCLUSIONS

Overweight asthmatic women have more pronounced systemic inflammation, but are less responsive to MCh. AMP responsiveness appeared to be comparable between both groups. Our findings suggest that overweight asthmatic women do not feature increased airway inflammation, but do represent a distinct phenotype as compared to normal weight patients.

The language of medically unexplained dyspnea

BACKGROUND

Medically unexplained dyspnea (MUD) refers to a condition characterized by a sensation of dyspnea and is typically applied to patients presenting with anxiety and hyperventilation without cardiopulmonary explanations for their dyspnea. The diagnosis is difficult. We investigated whether descriptors of dyspnea and associated symptoms of MUD are differentially diagnostic.

METHODS

A respiratory symptom checklist incorporating 61 spontaneously reported descriptors of dyspnea was administered to 96 patients with MUD and 195 patients with cardiopulmonary diseases. Symptom factors measuring different qualitative aspects of dyspnea were derived by a principal component analysis. The separation of two patient groups in terms of symptom factors was achieved by a discriminant analysis.

RESULTS

Five factors grouped different attributes of dyspnea: urge to breathe, depth and frequency of breathing, difficulty breathing and phase of respiration, wheezing, and affective dyspnea. The other five factors grouped symptoms of anxiety, tingling, cough and sputum, palpitation, and out of control. A discriminant analysis allowed to separate two patient groups (R(2) = 0.45, p < 0.0001). The presence of urge to breathe, affective dyspnea, anxiety, and tingling pointed to the diagnosis of MUD, whereas the reporting of wheezing, cough and sputum, and palpitation indicated cardiopulmonary diseases. The sensitivity was 85%, and specificity was 88%.

CONCLUSIONS

Descriptors of dyspnea and associated symptoms allows satisfactory separation of patients with MUD from patients with cardiopulmonary diseases. A prospective study will be required to test the validity and predictive values of the descriptor model in another cohort of patients.

Review of dyspnoea quantification in the emergency department: is a rating scale for breathlessness suitable for use as an admission prediction tool?

Acute shortness of breath is a potential marker of serious cardiopulmonary disease and requires rapid assessment. In our current health-care system, increasing pressure on the ED to limit costs and waiting times has resulted in the development of many clinical decision aids and admission prediction tools designed to assist ED physicians in meeting these demands. However, most of these tools are disease specific, and none are currently available for application to patients presenting to the ED with shortness of breath. Although somewhat limited, current evidence supports the utilization of a simple dyspnoea rating scale, to assist in the streamlining of clinical severity assessments and urgency evaluations, and to potentially provide useful information to facilitate rapid and accurate site-of-care decisions in this setting.

Descriptors and perception of dyspnea in African-American asthmatics

OBJECTIVE

This study explores self-reported perception of asthma symptoms in African-Americans.

METHODS

Qualitative methodology was used to analyze the responses from African-Americans within focus groups from Nashville, Tennessee.

RESULTS

Common symptoms were chest tightness, "breathing problems," and wheeze. Less commonly reported symptoms included cough, chest pain, dizziness, sweating, and "short of breath." A single participant reported nocturnal wheezing.

CONCLUSIONS

This study provides insight into the descriptors and perception of asthma symptoms in African-Americans. Understanding the descriptors of symptoms and disease severity in African-American patients may lead to more accurate diagnosis, treatment, and reduced mortality within this high-risk population.

Adrenergic responsiveness: FEV1 and symptom differences in Whites and African Americans with mild asthma

Decision-making about inhaler use is, in part, determined by the ability of asthmatic patients to compare their symptoms over time and to recall the previous response to the bronchodilator during an episode of asthma. The perception of airway symptoms across varied ethnic and cultural groups are poorly understood. Study purpose was (1) to determine if African Americans and Whites with mild asthma could accurately perceive bronchodilation and (2) to identify the word descriptors they used to describe their breathing. Sixteen African American and 16 White patients (34.5 +/- 9.7 years old, mean+/-SD) with mild atopic asthma (FEV1 > or =70% predicted normal) were given increasing doses of an inhaled bronchodilator (Albuterol) after a methacholine challenge. Albuterol (180 microg) was given, by spacer, at 15 min intervals until the FEV1 increased < 5%. Borg, VAS, and Word Descriptors were collected at baseline and after each dose of Albuterol. Baseline FEV1 after Methacholine provocation was 1.94 +/- .39 L for African Americans and 2.13 +/- .70 L for Whites. After 180 microg and again after 360 microg Albuterol, FEV1 increased to 2.88 +/- 0.48 L for African Americans and 3.37 +/- 0.91 L for Whites. But after 540 microg Albuterol, FEV1 decreased significantly (16%) to 2.42 +/- 1.19 L for African Americans while increasing only slightly to 3.47 +/- 0.95 L for Whites. After this dose, 10/16 African Americans felt "tight at the base of throat" (p < 0.01); 7/16 felt "speech-voice-tight" (p < 0.03) suggesting persistent airway discomfort despite marked improvement in FEV1, Borg and VAS scores compared with baseline values. Word descriptors by African Americans' are a more reliable measure of airway symptoms compared to FEV1, Borg or VAS.

Dyspnea and symptom amplification in asthma

BACKGROUND

The severity of a patient's asthma and the intensity with which he describes his dyspnea do not correlate.

OBJECTIVES

There is an indirect relationship between airway function in asthma and the intensity of dyspnea; this relationship is found only when the measure of a patient's general tendency to exaggerate the intensity of any somatic symptom is considered simultaneously.

METHODS

Lung function, including spirometry (forced expiratory volume in 1 s, FEV(1)) and plethysmography (airway resistance, R(aw)), dyspnea (Borg scale score) and the tendency to exaggerate (the somatosensory amplification scale score, SSAS) have been quantified in 42 stable asthmatic patients.

RESULTS

There was no correlation between the Borg score and any spirometric or plethysmographic measure in these subjects. By contrast, there was a moderate correlation between the Borg score and the SSAS (r = 0.36, p = 0.03). However, when FEV(1) or R(aw) (abscissa) and Borg scores (ordinate) were converted to residuals, there was a moderate correlation between the residuals and the SSAS score (for FEV(1), r = 0.33 and p = 0.05; for R(aw), r = -0.36 and p = 0.03).

CONCLUSION

A physician may make a reasonable estimate of an asthmatic patient's lung function from the intensity of his complaint only if he - the physician - considers the patient's tendency to symptom amplify as well.

A test of the symptom amplification hypothesis in patients with asthma

The present study sought to measure the accuracy of symptom reporting in patients with asthma by calculating the difference between a subjective rating of illness severity and an objective test of lung function (forced expiratory volume in 1 second). At issue was the hypothesis that self-reported "symptom amplification" or sensory awareness accounts for differences in the accuracy of symptom reporting. Spirometric examination was performed, and psychological tests of symptom amplification, emotional distress, and neuroticism were administered. Participants consisted of 42 consecutive patients seeking medical treatment of asthma. The disparity between symptom perception (assessed by a Borg scale) and a corresponding measure of lung capacity allowed us to identify patients who overreported their symptoms (amplifiers) along with those who underreported them (minimizers). After controlling for the effects of sex and psychological distress, a self-report measure of symptom amplification explained 15% of the variability in reporting accuracy. Related constructs such as somatization and neuroticism could not explain differences in reporting ability.

Cortical substrates for the perception of dyspnea

Dyspnea is a common, unpleasant, and impairing symptom in various respiratory diseases and other diseases. Despite growing understanding of the multiple peripheral mechanisms giving rise to dyspnea, little is known about the cortical mechanisms underlying its perception. The results of neuroimaging studies have shown that distinct brain areas process the dyspneic sensation, among which the anterior insular seems to be the most important. Based on the findings of the first relevant neuroimaging studies, this review describes the cortical structures associated with the perception of dyspnea. Moreover, similarities to the perception of pain are discussed, and implications for future research are provided.

Clinical and functional responses to salbutamol inhaled via different devices in asthmatic patients with induced bronchoconstriction

AIMS

This study aimed at evaluating changes in airway patency, lung volumes and perception of breathing discomfort intensity following salbutamol administration via the Diskus dry-powder inhaler (DPI) or a pressurized metered-dose inhaler with the Volumatic valved holding chamber (pMDI + Volumatic) in asthmatic patients with methacholine-induced bronchoconstriction.

METHODS

On six different study days, 18 patients inhaled methacholine until forced expiratory volume in 1 s (FEV(1)) decreased by approximately 35% of baseline. Following placebo, 200 and 400 microg of salbutamol through the pMDI + Volumatic or the Diskus, changes in FEV(1), volume-adjusted mean forced expiratory flow from 25 to 75% of the forced vital capacity (isoFEF(25-75)), lung volumes and breathing discomfort intensity, assessed by visual analogue scale (VAS) score, were repeatedly measured over a 60-min observation period.

RESULTS

Induced bronchoconstriction was accompanied by obvious reductions in lung volumes and increases in VAS score. After salbutamol administration, FEV(1) and VAS score changes were similar in all experimental conditions. However, following 400 microg salbutamol via pMDI + Volumatic, isoFEF(25-75) values increased up to 4.48 l s(-1) (95% confidence interval 4.06, 4.90), a significantly (P < 0.01) higher value than those attained in all other experimental conditions. Independently of the salbutamol dose, lung volumes rose to significantly (P < 0.01) higher levels in pMDI + Volumatic than in Diskus trials. The low salbutamol dose via the pMDI + Volumatic and the high dose via the DPI increased isoFEF(25-75) and lung volumes to similar extents.

CONCLUSIONS

Salbutamol via the pMDI + Volumatic provides greater isoFEF(25-75) and lung volume increases in asthmatic patients with induced bronchoconstriction; salbutamol-induced changes in VAS scores poorly reflect those in small airway patency. The lack of differences in FEV(1) increases observed after 200 and 400 microg salbutamol may reflect attainment of the flat portion of the dose-response curve using either device.

Profiles of measured and perceived bronchodilation. A placebo-controlled cross-over trial comparing formoterol and salmeterol in moderate persistent asthma

BACKGROUND AND OBJECTIVE

Long-acting beta(2)-agonists have acquired an indispensable position in the management of bronchial symptoms in patients with asthma. The objective of this study was to compare onset-of-action and clinical effectiveness of formoterol and salmeterol during 2 weeks of treatment. We also investigated the association between bronchodilator effects and perceived relieve of dyspnoea.

METHODS

A multi-centre randomized double-blind placebo-controlled cross-over trial was performed in 35 subjects with moderate persistent asthma. Treatment periods existed of 2 weeks formoterol (12 microg bid), salmeterol (50 microg bid) and placebo, all administered by pressurized metered dose inhaler. FEV(1) and Visual Analogue Scale (VAS) scores were repeatedly measured until 180 min post-bronchodilation (post-BD), before as well as after each treatment period. Onset-of-action was defined as a >/=15% increase in FEV(1). Subjects kept diaries of morning and evening PEFR values and use of rescue bronchodilator.

RESULTS

Formoterol and salmeterol both caused a significant increase in FEV(1) (0.45L [95% CI 0.01, 0.80] and 0.27L [95% CI 0.08, 0.62] respectively). At 3' post-BD, three times as many subjects demonstrated onset-of-action on formoterol compared to salmeterol (36% versus 13%, P = 0.063), at 6' post-BD 42% versus 27% (P = 0.063). VAS scores were similar for formoterol and salmeterol at pre-treatment assessment, but tended to be higher for formoterol after 2weeks treatment. No differences between formoterol and salmeterol were observed for PEFR values or use of rescue medication. 50% of the subjects preferred formoterol, 29% salmeterol (P < 0.001). Significant associations between FEV(1) and VAS ratings existed only at 10', 15' and 30' post-BD, not before or after these time points.

CONCLUSION

The earlier described faster onset-of-action of formoterol as compared to a equipotent dosage of salmeterol was confirmed in this study. Perception of decreasing airflow obstruction may be delayed after acute bronchodilation.

The perception of dyspnea after bronchoconstriction and bronchodilation in patients with asthma

BACKGROUND

It is well documented that the perception of dyspnea (POD), subjectively reported by patients, is an important index used to guide treatment. The severity of dyspnea following methacholine-induced bronchoconstriction and added mechanical loads is increasing in popular. No formal attention has been addressed to the reduction in dyspnea following bronchodilators.

STUDY OBJECTIVE

To investigate if the magnitude of dyspnea perceived by a subject is independent on the direction (e.g., bronchoconstriction or bronchodilation) of the change in airway resistance.

METHODS

The POD was measured in 26 mild moderate asthmatic patients following bronchodilation, using beta2-agonists, and following bronchoconstriction, induced by methacholine challenge, to almost the same magnitude.

RESULTS

The increase in forced expiratory volume in 1 s (FEV1), 30 min after the inhalation of beta2-agonist (mean +/- SEM 22.3 +/- 0.8%), was associated with a statistically significant decrease (P < 0.005) in the POD. The mean decrease in FEV1 following methacoline challenge, was 23 +/- 0.7% and was followed by a statistically significant increase (P < 0.005) in the POD. The magnitude of the decrease in the POD following albuterol was almost identical to the magnitude of the increase in the POD following methacholine.

CONCLUSIONS

In stable mild-moderate asthmatic patients, the changes in the magnitude of dyspnea, perceived by a subject, is independent on the direction of the change in the FEV1.

Leukotriene receptor antagonists in asthma therapy

In persons with asthma, the cysteinyl leukotrienes possess multiple inflammatory properties in vitro and have long been considered to be a potentially important mediator of asthma and an attractive target for therapeutic intervention. Controlled clinical trials have documented the efficacy of leukotriene receptor antagonists in asthma treatment, but reservations about their use for asthma therapy center on two main issues: the heterogeneity of patient responses and their reduced potency relative to other asthma medications. For example, leukotriene receptor antagonists also have been shown to be less efficacious than inhaled corticosteroids for several end points, including symptom relief, reduced markers of inflammation, and improved pulmonary function. This review explores several underappreciated aspects of asthma therapy: heterogeneity of patient responses to medication, the failure of symptoms to correlate with commonly used end points, and the potential of delivery to distal airways for producing important and novel benefits.